HELP MY XEDOS

Mazda 626

I HAVE MAZDA XEDOS 1995 128MILEAGE AND ITS V6 AND ITS AUTOMATIC TRANSMISSION. WHEN I START IT AND PUT IT TO DRIVE OR REVERSE, IT DOES NOT MOVE UNTIL I WAIT SOME SECONDS, BEFORE IT PICKS AND THEN WHEN I STOP ITS DOES IT AGAIN. AND WHEN ON THE HIGHWAY IT JUST CUTS OFF TILL I STOP ACCELERATING AND WAIT A MINUTE AND ALL OVER AGAIN. PLEASE WHAT CAN THE PROBLEM BE? WE HAVE REPLACED THE TRANSMISSION FLUID AND ITS STILL THE SAME